To give a quantitative estimation of the upper limit for the spin of \(N^*\)  produced from \(J/\psi \)  and \(\psi (2S)\)  decays, it is important to study the effective interaction radius \((r_{{\text{eff}}})\)  for these processes.
With \(\bar{L}= r_{{\text{eff}}}\times p\) , \(r_{{\text{eff}}}\)  can be determined by calculating the average orbital angular momentum \((\bar{L})\)  and the relative momentum \((p)\) .
This article mainly studies the interaction radius of the \(\psi (1^-) \rightarrow B_8 \bar{B}_8\) .
In this work, we construct the amplitudes within the covariant L-S scheme  [1]}, [2]}, [3]}, [4]}, and then we do a PWA based on the BESIII data [5]}, [6]}, [7]}, [8]}, [9]}, [10]}, [11]}.
From the PWA, the ratio between the S-wave and D-wave contributions can be computed, and the average orbital angular momentum \((\bar{L})\)  of \(B\bar{B}\)  can be deduced.
At last, the effective ranges of these reactions can be obtained.
